Early pace setter Bob Jungels of Luxembourg finished third at 9sec ahead of American Andrew Talansky.

"I'm a bit surprised to be honest, I didn't expect to win. It's a result that confirms the work done in training and the fact that I'm in form," Froome said afterwards.

Froome trailed Italy's Vincenzo Nibali by 2sec at the intermediate checkpoint following the stage's lone climb, the fourth category Montee de l'Observance, while holding a slender 1sec advantage over Spain's Contador.

However, the Team Sky rider set a blazing pace over the second half of the circuit to propel himself into the race leader's yellow jersey and overhaul Nibali, who finished the day down in a tie for eighth at 13sec.

"During the course I didn't have any information regarding the times of my rivals, I preferred to just focus on myself and what I was doing," said Froome.

"I only knew that the final 4km were difficult going into the wind, so I saved my strength for that part."

Froome, who will also try to defend his Tour de France title next month, admitted that he had not anticipated wearing yellow quite so soon.

"It's a bit of an unexpected situation because I didn't expect to find myself in this position but it's great to not have any time to make up.

"I'm going to defend the yellow jersey even if I didn't think I'd have it right now.

"The Dauphine this year is really hard right from the opening stages. I think tomorrow again we can expect a really big race in the mountains," added the Team Sky rider.

The second leg is a 156km ride between Tarare and the Col du Beal, with a final climb of 13.6km at 6.6 percent.